Stimulation of Bactericidal and Fungicidal Activity of Neonatal Monocytes by Immunoactivating Peptide

ABSTRACT

PURPOSE: To evaluate the function of Trp-Lys-Tyr-Met-Val-D-Met (WKYMVm) in human neonatal monocytes. METHODS: The peptide, Trp-Lys-Tyr-Met-Val-D-Met (WKYMVm), was synthesized, purified, and prepared in the Peptide Library Support Facility at Pohang University of Science and Technology. Female Sprague-Dawley rats (200+/-10 g) were preinfected with S. aureus and treated with WKYMVm through femoral vein. At various time points, blood samples were obtained by puncture of femoral artery and the serum was plated on the nutrient agar plate. The number of viable bacteria was determined by counting the number of bacterial colonies. In addition, using S. aureus and C. albicans, we evaluated the bactericidal and fungicidal activities of neonatal monocytes, which were separated from umbilical cord blood by Ficoll gradient. RESULTS: The numbers of bacteria in the blood of WKYMVm-treated rats were rapidly decreased with time, as compared with those of the untreated rats. The peptide treatment enhanced the bactericidal activity in vivo within 10 minutes. In neonatal monocytes, WKYMVm stimulated the intracellular killing of S. aureus in a dose dependent manner, showing the maximum effect at 100 nM. WKYMVm stimulated the phagocytic and fungicidal activities against C. albicans in a dose dependent manner, with the maximum effect at the 100 nM. CONCLUSION: These results suggest that WKYMVm may be an effective agent against the neonatal infections.